Rectangular silencers with splitters (baffles) are the basis for many applications related to soundproofing when it is desired to limit the propagation of noise through openings with a circulating fluid. In many common cases (e.g. air conditioning networks, ventilation of equipment premises or of other rooms, ventilation systems for enclosures), splitters are most of the time continuous, i.e. with a height equal to that of the duct in which they are inserted, which facilitates their attachment. In other cases where the acoustic and aerodynamic performance outside the norm are sought (e.g. air intake or exhaust silencers for gas turbines), use of discontinuous splitters can be considered e.g. where the consideration of continuous spitters does not allow obtaining the insertion loss required for both low frequency and high frequency.
Because then, the sound-absorbing lining surface (in general a porous medium, where appropriate lwith a surfacing and with a perforated protection) in contact with the fluid, distributed differently, allows - all things being equal as to the open area ratio and the free passage area -different interactions influencing the acoustic performance without modifying the flow speed of the fluid, and therefore with - roughly - an aerodynamic performance (i.e. a total loss of pressure) and a self noise (due to the flow) being similar.
ITS has integrated the sizing of silencers made of discontinued splitters (baffles) to the simulation software SILDIS® (this is the subject of Module 1A).
Calculation routines have been implemented to calculate the insertion loss accounting the self noise of such equipments that characterizes their acoustic performance, and to calculate the total pressure loss (sometimes called pressure drop) that characterizes their aerodynamic performance.
Following the modification operationsof the acoustics calculation software SILDIS®, the comparison of simulation results with bibliographic data (results of measurements, results of calculations by others ...) has shown a satisfactory agreement for numerous combinations of geometrical parameters defining the silencers and for various fluid speeds.
The expected result of improvements to the software SILDIS® - for the sizing of silencers made of discontinued splitters (baffles) - is an enrichment of the range of industrial silencers of which design is very demanding given the considered flow rates and given the expected performance in terms of aerodynamics often antagonist with the requested acoustic performance in the context of protection of workers, and/or of preservation of environment (thus especially in the energy production sector).